Triazeno compounds

ABSTRACT

CERTAIN DERIVATIVES OF THE IMIDAZOLE HETEROCYCLIC RING WHICH IS A 5-MEMBERED DIAZA STRUCTURE CONTAINING TWO NITROGEN ATOMS AND TWO DOUBLE BONDS ARE DESCRIBED. SINCE TAUTOMERIC STRUCTURES ARE POSSIBLE, SUBSTITUENTS IN THE 4 AND 5 POSITIONS ARE WRITTEN THUS: 4(OR 5) AND 5(OR 4). THE PRESENT COMPOUNDS ARE TRIAZENO AND DIAZO DERIVATIVES OF IMIDAZOLE CARBOXYLIC ACID ESTERS. THE FORMULAS FOR THE COMPOUNDS OF THE PRESENT INVENTION ARE SET OUT BELOW:   4-(R1-OOC-),5-(N2-)IMIDAZOLE   4-(R1-OOC-),5-(R2-N(-R3)-N=N-)IMIDAZOLE   R1=ALKYL, SUBSTITUTED ALKYL, ARYL AND ACID ADDITION SALTS THEREOF; R2=ALKYL, SUBSTITUTED ALKYL, ARYL; R3=H, ALKYL, SUBSTITUTED ALKYL AND ARYL.

States 3,649,613 TRIAZEND COMPOUNDS Charles A. Krauth, Taejon, Korea, and Yoder Fnlmer Shealy and Clinton Allen ODell, Birmingham, Ala, assignors to the United States of America as represented by the Secretary of the Department of Health, Education, and Welfare No Drawing. Filed Sept. 14, 1967, Ser. No. 667,659

Int. Cl. C07c 115/00 U.S. Cl. 260-140 10 Claims ABSTRACT OF THE DKSCLOSURE Certain derivatives of the imidazole heterocyclic ring which is a S-membered diaza structure containing two nitrogen atoms and two double bonds are described. Since tautomeric structures are possible, substituents in the 4 and 5 positions are written thus: 4(0r 5) and 5(or 4). The present compounds are triazeno and diazo derivatives of imidazole carboxylic acid esters. The formulas for the compounds of the present invention are set out below:

FORMULA I i N COOR \/(lOR l 1i 2 T H R =alkyl, substituted alkyl, aryl and acid addition salts thereof;

R =alkyl, substituted alkyl, aryl;

R =H, alkyl, substituted alkyl and aryl.

hibit strong antifungal activity. Certain other compounds of the present invention additionally exhibit antialgal and antiprotozoal activity. The present group of compounds having combined antifungal and antibacterial activity find present utility in sanitizing sheets, bed linen, etc., in hospitals. Aqueous solutions and solvent dispersions in concentrations of only a few parts per million have exerted powerful sanitizing action.

The compounds of the present invention may be conveniently prepared using as known starting materials the R 5 (or 4)-aminoirnidazole-4(or 5)-carboxylate where R is selected to provide the proper ester substituent. Conventional nitrite diazotization of the compounds in the cold with excess mineral acid gives the intermediate diazo compounds which may be extracted with organic solvents and separated as desired. Excess nitrite is destroyed by known reagents such as sulfamic acid.

The triazeno moiety providing the R and R of the final compounds may be achieved by amination of the reaction diazo intermediate compound at an alkaline pH of 9-10 using a primary or secondary amine with the desired su-bstituent groups.

atet The shift of the pH from the acid of the diazo preparation wherein the reaction mixture was strongly acid to the triazeno preparation where the reaction mixture is slightly basic is usually achieved by the simple addition of the basic amine without subsidiary alkaline reagents.

The ester acid addition salts are prepared by reaction with the appropriate acid as HCl, to give more soluble compounds. The triazeno compounds of the present invention may be recovered by extraction with a variety of organic solvents, followed by distillation. The more hydrophobic compounds precipitate more readily from hydrophilic type solvents. A particularly useful solvent for purifying the triazeno compound is a mixture of ethyl acetate-hexane.

PRIOR ART The prior art picture in which the present invention falls is limited in scope. A portion of the present development was described in the following article, A new Antifugal and Antibacterial Agent, Methyl 5(or 4)- 3,3-dimethyl-l triazeno)imidazole-4(or 5)-carboxylate, Shealy, et al., Jour. of American Pharmaceutical Association, vol. 56, No. 1 (January 1967), pp. 147148.

Analogous carboxamide compounds showing antileukemic activity but lacking the present broad spectrum microbial activity are described in previous publications of the same authority, Shealy et al., Biochem. Pharmacol, 2, 674 (1962), and Shealy et al., Nature, 210, 208 (1966).

Comparative experiments showing the lack of activity of analogous prior art carboxamides to typical compounds showing novel broad spectrum microbial activity of the present esters are set out more fully in Examples 26 and 27.

SOLUBILITY The compounds of the present invention, in addition to fair aqueous solubility, are generally soluble in polar and organic solvents such as lower aliphatic alcohols, such as methanol and ethanol; halogenated compounds of the methane series such as chloroform; alkyl esters of aliphatic acids such as ethyl acetate. The ester acid addition salts such as hydrochloride, hydrobromide, hydroiodide find greater hydrophilic solubility due to aqueous affinity of the acid and this is particularly true of the mineral acid addition salt group,

Suitable salts are, for example, the ester acid addition salts from mineral acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid and orthophosphoric acid, or organic acids such as acetic acid, propionic acid, pivalic acid, succinic acid, maleic acid, fumaric acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, L-ascorbic acid, benzoic acid, salicylic acid, methyl sulfonic acid, ethyl disulfonic acid, p-toluenesulfonic acid, naphthalene disulfonic acid and ,B-hydroxyethyl sulfonic acid.

UTILITY The instant compounds have present utility as sanitizing compounds. Thus, a hospital blanket or a toy from the OT. department of the hospital when soiled and contaminated by a mixture of pathogenic organisms including both bacteria and fungi, may be sanitized immediately by soaking or spraying the article with solutions of 50 to 250 ppm. of the active compound. Aqueous solu tions of the water-soluble acid addition salts of the esters, alcoholic sprays of the more hydrophobic compounds and foamite applications to other articles about the hospital, such as soiled rugs, illustrate the present utility of the compounds of this invention.

ACTIVITY The triazeno imidazole carboxylic acid esters and the 5-diaZoimidazole-4-carboxylic acid esters of this invention have inhibitory activity in several different types of microorganisms. Methyl (or 4)-(3,3-dimethyl-1-triazeno)imidazole-4(or 5)-carboxylate, the compound of Example 1, for example, inhibits the growth of a wide variety of yeast, filamentous fungi, gram positive and gram negative bacteria, mycobacteria and algae. The antimicrobial activity of these compounds is exemplified by inhibition by methyl 5 (or 4 3 ,3 -dirnethyl-1-triazeno imidazole-4 (or 5 -carboxylate (Example 1), ethyl 5 (or 4)-(3-cyclohexyl-3- methyll-tri'azeno imidazole-4 (or 5 -carboxylate Example 9), or methyl 5-diazoimidazole-4-carboxylate (Example 4) of Streptococcus faecalis, Staphylococcus aurcus, Bacillus subtilis, Sarcina lutea, Escherichia coli, Salmonella typhimurium, Proteus vulgaris, Pseudomonas aeragin'osa, Mycobacterium smegmatis, Candida albicans, Hansenula winkei, Saccharomyces cerevz'siae, Fusariztm oxysporum, Penicillium roqueforti, Chlorella pyrenoidosa, and strains of these microorganisms resistant to the action of certain known chemotherapeutic agents.

PROCESS The triazeno esters may be prepared conveniently from the ester of the corresponding amino compound of the 4(or 5)-carboxylic acid and treating this amino compound with a diazotizing reagent and an acid. The starting materials are well known in the art, for example, the methyl 4(or 5 )-amino imidazole-5(or 4)-carboxylate used in Examples 1, 2, 3, 4 or 7 and 19 is cited in the loot. Gen. Chem., USSR, 29, 2366-2368 (1959), a translation of Russian Zhur. Obshchei Khim., 29, 2401 (1959). This Russian article has not only prepared the methyl and ethyl esters, but the alkyl series including the mineral acid addition salts. An additional citation to the same amino starting materials is the Jour. Chem. Soc., 1942, p. 232, Allsebrook et al. Additionally, where the corresponding nitro derivative is used as the precursor for the amino as in Example 14, its formula and preparation are described in Berichte, 56, pp. 683-686 (1923). The triazeno-imidazole esters are readily prepared by treating an ester (with the desired R substituent) of 5 (or 4)-aminoimidazole-4 (or 5)-carboxylic acid with a diazotizing agent and an acid, in order to form an ester of 5-diazoimidazole-4-carboxylic acid which is the intermediate diazo compound. Subsequently, the requisite amine (with the desired R and R substituents) is introduced in sufiicient quantity to neutralize the acid and to react with the diazo group in the cold. Thus, diazotization of methyl 5(or 4)-aminoimid azole 4(or 5)-carboxylate with sodium nitrite and hydrochloric acid followed by addition of 25 aqueous dimethyl amine and extraction of the reaction mixture with chloroform reveals methyl 5 (or 4)-(3,3-dimethyl-l-triazeno) imidazole-4 (or 5) -carboxylate.

Alternatively, the process may be interrupted to recover the active but sporadically unstable diazo compounds in the form of the intermediate 5-diazoimidazole-4-carboxylic acid ester which may be conveniently extracted from the aqueous diazotization mixture with organic solvents such as chloroform, or depending on water solubility may be recovered as a precipitate from the solution and collected by filtration. Such a procedure is taught more fully as in Examples 4 through 6 inclusive. Additionally, the diazo derivative may then be treated with an appropriate amine in a two-step or interrupted process to produce the final preferred triazeno compounds.

In general, the production of the diazo compound or diazonium salt which is a nitrous acid derivative of the heterocyclic amine follows conventional procedure in the type reaction for the production of diazo compounds, as for example, set out in Karrer Organic Chemistry, 4th Ed., 1950, pg. 472. The amine and the nitrite salt are reacted in approximately equimolar quantities in the presence of a general excess of at least 2.5 mols of mineral acid, as for example, hydrochloric acid used in many of the examples. The reaction is carried out by immersing in an ice salt bath to reduce the temperature to a range of about 4 0-5". The excess of the mineral acid serves to drive the reaction toward the right and cold treatment is used because many diazo and diazonium compounds are unstable at high temperatures. Thus the diazo compound may be separately recovered.

The production of the triazeno compound is readily made after destruction of excess nitrite with an agent such as sulfamic acid and when the required primary or secondary amine is added the reaction goes at a slightly alkaline pH of 9-10. The compound may be extracted with chloroform, recrystallized from methanol, dried and recovered as the triazeno compound.

EXAh IPLE 1 Methyl 5 (or 4) 3,3-dimethyll-triazeno) imidazole-4 (or 5 -carboxylate A solution of 5.4 g. of methyl 5(or 4)-aminoimidazole- 4(or 5)-carboxylate in 216 ml. of a one-normal (l N) solution of hydrochloric acid was treated with activated carbon to remove colored impurities. To the colorless filtrate, immersed in an ice-salt bath, was added dropwise during 0.5 hr. a solution of 2.95 g. of sodium nitrite in 25 ml. of water. The yellow solution was stirred in the ice-salt bath for an additional hour, excess nitrite was destroyed by the addition of sulfamic acid, and 55 ml. of 25% aqueous dimethylamine was added. This solution (pH 9-10) was stirred for 1 hour in the ice bath and then extracted six times with 250 ml. portions of chloroforms. The extracts were combined; the total extract was dried with magnesium sulfate and treated with activated carbon; and the filtrate from the carbon Was freed of solvent under reduced pressure. The pink product was dried in vacuo over phosphorus pentoxide at room temperature, wt., 4.9 g. The yields of crude product ranged from 66- 83%. A solution of the crude product in methanol was stirred with activated carbon, filtered, and reduced to dryness in vacuo. The residue was treated with activated carbon in methanol a second time, and the resulting white solid was dried in vacuo over phosphorus pentoxide at room temperature: weight, 4.3 g.; l\/i.P. l63-165 with decomposition; one spot on a thin-layer chromatogram (silica gel H, 9:1 chloroform-methanol). The methyl 5 (or 4)-(3,3-dirnethyl-1-triazeno)imidazole 4( or 5 )-carboxylate obtained in this manner displayed ultraviolet absorption maxima in methanol at 233 mu and 328 mg and prominent infrared absorption bands near 1695 cur- 1440 cm.- 1315 cmf 1070 cm.

Analysis.Calcd. for C H N O- (percent): C, 42.64; g, 5.563; N, 35.51. Found (percent): C, 42.90; H. 5.64;

EXAMPLE 2 Methyl 5 or 4) 3-n-butyl-3 -methyl-1 -triazeno) imidazole-4 (or 5 -car boxyl ate The procedure of Example 1 was employed with the following exceptions: (l) the reaction solution obtained after the addition of the water solution of sodium nitrite to the hydrochloric acid solution of methyl 5(or 4)- aminoimidaZole-4(or 5 )-carhoxylate was stirred for 0.5 hour, and (2) methyl-n-butylarnine was used in lieu of 25% aqueous dimethylamine and was added in sufiicient quantity to raise the pH at least to 9. The product precipitated from the reaction mixture and was collected by filtration, washed well with water, and dried thoroughly at room temperature. From 7.5 g. of methyl 5 (or 4)- aminoimidazole-4(or 5)-carboxylate was obtained 9.1 g. (72% yield) of white crystals of methyl 5 (or 4)-(3-nbutyl-3-methyl-l-triazeno) imidazole-4 (or 5 -carboxylate: M.P., 167168 with decomposition.

Analysis.Calcd. for C10H1'7N5O2 (percent): C, 50.19; H, 7.16; N, 29.27. Found (percent): C, 50.25; H, 7.23; N, 29.21.

EXAMPLE 3 Methyl 5 (or 4)-(3-cyclohexyl-3-rnethyl-l-triazeno) imidazole-4(or 5) -carboxylate The procedure of Example 2 was followed with the exception that methylcyclohexylamine was used in lieu of methyl-n-butylamine. From 5.5 g. of methyl 5(or 4)- aminoimidazole-4(or 5)-carboxylate was obtained 7.2 g. of methyl 5(or 4)-(3-cyclohexyl-3-methyl-1-triazeno) irnidazole-4(or 5)-carboxylate as white crystals: M.P., 182-184 with decomposition.

Analysis.-Calcd. for C H N O (percent): C, 54.32; H, 7.22; N, 26.40. Found (percent): C, 54.50; H, 7.38; N, 26.25.

EXAMPLE 4 Methyl 5-diazornidazole-4-canboxylate A solution of g. of methyl 5 (or 4)-aminoimidazole- 4(or 5)-carboxylate in 200 ml. of 1 N hydrochloric acid was treated with activated carbon to remove colored impurities. To the filtrate immersed in an ice-salt bath was added dropwise during 5 min. a solution of 5.46 g. of sodium nitrite in 20 ml. of water. The reaction mixture was stirred for 1.5 hrs. and then extracted 10 times with ZOO-ml. portions of chloroform. The extracts were combined; the total extract was washed with saturated sodium chloride solution, filtered, and dried with magnesium sulfate. The filtrate from the drying agent was evaporated under reduced pressure at temperatures below 30, and the yellow crystalline methyl 5-diazoimidazole-4-carboxylate so obtained was dried further in a vacuum at room temperature; weight, 8.13 g. (75% yield); M.P., 95-96". The ultraviolet absorption spectrum of methyl 5-diazoimidazole-4-carboxylate in phosphate buffer at pH 7 displayed a maximum at 314 m and a shoulder at 270 m its infrared spectrum included prominent bands near 2180 CHI-1 due to the diazo group and near 1700 cm? due to the ester group.

Analysis.-Calcd. for C H N O (percent): C, 39.48; H, 2.65; N, 36.84. Found (percent): C, 39.81; H, 2.98; N, 36.51.

EXAMPLE 5 Ethyl 5-diazoimidazole-4-carboxylate To a solution of 1.36 g. of ethyl 5(or 4)-aminoimidazole-4(or 5)-carboxylate hydrochloride in 20 ml. of 1 N hydrochloric acid at 0 was added a solution of 546 mg. of sodium nitrite in 5 ml. of water. The pale yellow solution was stirred at 0 for 1 hour and then extracted with four -ml. portions of chloroform. The chloroform extracts were combined, washed with a saturated solution of sodium chloride, dried with magnesium sulfate, filtered, and concentrated under reduced pressure at room temperature. The residual light yellow oil (1.1 g.) crystallized to a yellow crystalline solid; M.P., 45-46 dec. A strong band near 2200 cm. characteristic of the diazo group, was present in the infrared spectrum.

Analysis.Calcd. for C H N O (percent): C, 43.38; H, 3.64; N, 33.72. Found (percent): C, 43.40; H, 3.58; N, 33.94.

EXAMPLE 6 Octyl 5-diazoimidazole-4-carboxylate Octyl 5(or 4)-aminoimidazole-4(or 5 )-canboxylate hydrochloride was diazotized in hydrochloric acid by a procedure similar to those of Examples 4 and 5. The product precipitated and was separated by filtration, washed thoroughly with water, and dried under reduced pressure; yields were 75-85%; M.P., 4445. The product may be purified further by dissolving it in acetone, treating the acetone solution with activated carbon, and evaporating the acetone from the filtrate under reduced pressure. The residual oil crystallizes to a yellow crystalline solid; M.P., 45-46. The infrared absorption spectrum included strong absorption bands near 2190 cm? and 1730 GEL-1, char- 6 acteristic of a diazo group and an ester group, respectively.

Analysis.Calcd. for C I-1 N 0 (percent): C, 57.58; H, 7.25; N, 22.38. Found (percent): C, 57.82; H, 7.31; N, 22.59.

EXAMPLE 7 Methyl 5 (or 4) 3- (Z-hydroxyethyl) -3-methyl- 1- triazeno] imidazole-4(or 5 -carboxylate Part A.- he procedure of Example 1 was followed with the exception that N-methylethanolamine was used in lieu of 25% aqueous dimethylamine. The chloroform extract afforded a clear viscous oil, which was crystallized from a mixture of methanol, ethyl acetate, and hexane. The yield of white crystalline product was 10.5%; M.P., 15 6-15 8 with decomposition. An additional quantity was isolated by neutralizing the water layer remaining from the chloriform extraction with hydrochloric acid, reextractiug the neutral water layer with chloroform, and crystallizing the oil obtained from the second chloroform extract from a mixture of methanol, ethyl acetate, and hexane. The second portion, M.P., 156-157 dec., amounted to a yield of 14.5% and raised the total yield to 25%.

Part B.-A solution consisting of 12.5 ml. of N-methylethanolamine in ml. of ethyl acetate was prepared and was shielded from light. To this solution 3.14 g. of methyl S-diazoimidazole-4-carboxylate was added in portions. This addition was made over a period of 11.5 hrs., and the reaction mixture was stirred for an additional 2.5 hrs. in the dark. The precipitated product was collected by filtration, washed thoroughly with ethyl acetate, and dried under reduced pressure: weight, 4.4 g. (98% yield); M.P., 156-157 dec.

Analysis.Calcd. for C H N O (percent): C, 42.29; H, 5.77; N, 30.82. Found (percent): C, 42.17; H, 5.87; N, 30.64.

EXAMPLE 8 Ethyl 5 (or 4)-(3-n-butyl-3-methyl-l-triazeno)imidazole- 4(or 5 )-carboxylate Part A.-A solution consisting of 4.75 g. of ethyl 5- diazoimidazole-4-carboxylate in 75 ml. of anhydrous ethyl acetate was prepared and was shielded from light. To this solution was added 20 ml. of methyl-n-butylamine, and the mixture was cooled to prevent an excessive rise in the temperature. The mixture, in which a white precipitate soon began to form, was stirred overnight at room temperature in the dark. The white crystalline product was collected by filtration, washed with ethyl acetate, and dried under reduced pressure: weight, 3.7 g.; M.P., -131. Additional ethyl 5(or 4)-3-n'butyl-3- methyl-1-triazeno)imidazole-4(or 5 )-carboxylate was obtained by diluting the ethyl acetate filtrate with hexane and chilling. White needles were removed by filtration, washed with ethyl acetate, and dried under reduced pressure: weight, 2.36 g.; M.P., 130-131".

Analysis.Calcd. for C H N5O (percent): C, 52.16; H, 7.56; N, 27.65. Found (percent): C, 52.28; H, 7.64; N, 27.50.

Part B.-To a solution of 5.0 g. of ethyl 5 (or 4)-aminoimidazole-4(or 5)-carboxylate hydrochloride in 74 ml. of 1 N hydrochloric acid at 0 C. was added during a period of 15 min. a solution of 2.0 g. of sodium nitrite in 20 ml. of water. The resulting solution was stirred in an ice bath for 30 min., the excess nitrite was destroyed with sulfamic acid, and 30 ml. of methyl-n-butylamine was then introduced. The mixture was stirred for 1.5 hr. and then filtered to remove the first portion of product, which was washed thoroughly with water and dried under reduced pressure: weight, 3.43 g.; M.P. 130-131. The filtrate was extracted twice with 50-rnl. portions of chloroform and the extracts were combined. The total chloroform extract was washed with a saturated aqueous sodium chloride solution, treated with activated carbon, and dried with magnesium sulfate. Evaporation of the chloroform under reduced pressure left an oil that crystallized when it was triturated with a 4:1 mixture of hexane and ethyl acetate. Recrystallization of this solid from a mixture (1: 1) of ethyl acetate and hexane yielded a second portion of crystalline ethyl (or 4)-3-n-butyl-3- methyl-l-triazeno)imidazole-4(or 5 )carboxylate: weight, 2.28 g.; M.P., 130-131. The infrared spectra of both this material and of the first portion showed them to be identical with specimens of this compound prepared by the procedure of Part A.

EXAMPLE 9 Ethyl 5 (or 4) 3-cyclohexyl-3-methyl-l-triazeno imidazole-4-(or 5 -carboxylate Part A.-The procedure of Part A of Example 8 was applied to a reaction of ethyl 5-diazoimidazole-4-carboxylate (4.5 g.) and methylcyclohexylamine ml.), in stead of methyl-n-butylamine, in ethyl acetate (125 ml.). The reaction mixture was stirred for a period of 2 hr. at room temperature instead of the overnight-stirring of Example 8, Part A. The white crystalline product obtained by filtering the reaction mixture represented a yield of 58% (4.3-1 g.); M.P., 170 dec. The infrared spectrum of this material was identical with that of the analytical sample of Part B. A second crop of the same product amounting to a yield of 16.5% (1.25 g.) was obtained by diluting the filtrate from the first crop with hexane and chilling.

Part B.The procedure of Part B of Example 8 was employed with the exception that methylcyclohexylamine was used in lieu of methyl-n-butylamine. The reaction mixture was filtered to remove a precipitate that represented a yield of 80% of ethyl 5(or 4)-(3-cyclohexyl-3- methyl-l-triazeno)irnidazole-4(or 5 )-carboxylate; M.P., 168-170 with decomposition.

Analysis.-Calcd. for C H N O (percent): C, 55.89; H, 7.58; N, 25.07. Found (percent): C, 55.78; H, 7.58; N, 24.96.

EXAMPLE 10 Ethyl 5(or 4)-(3,3-dimethyl-l-triazeno)imidazole- 4(or 5)-carboxylatc Part A.Dimethylamine gas was passed into 75 ml. of ethyl acetate until 13.9 g. had been absorbed. To this solution, cooled with an ice bath, was added, within a 3-minute interval, a solution of 4.7 g. of ethyl S-diazoimidazole-4-carboxylate in ml. of ethyl acetate. A white solid began to precipitate almost immediately. The mixture was stirred at ice-bath temperature for 2 hr., and the white crystalline ethyl 5(or 4)-(3,3-dimethyl-l-triazeno)imidazole-4(or 5 )-carboxylate was separated by filtration, washed with ethyl acetate, and dried under reduced pressure: weight, 3.92 g.; M.P. l74-175 dec.

Analysis.-Calcd. (percent): C, 45.50; H, 6.21. Found (percent): C, 45.54; H, 6.37.

A second crop of slightly less pure product, which amounted to 400 mg., was precipitated from the filtrate by the addition of ether.

Part B.-The procedure of Part B of Example 8 was employed with the exception that 25% aqueous dimethylamine (110 ml.) was used in lieu of methyl-n-butylamine. After 1 hr. of stirring, the reaction mixture was extracted four times with chloroform. The extracts were combined; the total extract was washed with saturated aqueous sodium chloride solution and dried with magnesium sulfate; and the chloroform was evaporated under reduced pressure. From 10 g. of ethyl 5(or 4)-aminoimidazole-4( or 5 )-carboxylate hydrochloride was obtained 9.54 g. of the dimethyltriazeno derivative: M.P., 174l7S dec.

Analysis.Ca1cd. for C H N O (percent): C, 45.50; H, 6.21, N, 33.16. Found (percent): C, 45.82; H, 6.24; N, 33.30.

EXAMPLE l1 Octyl 5(or 4) -(3-n-butyl-3-methyl-1-triazeno)imidazole- 4(or 5 )-carboxylate A solution of 24.0 ml. of methyl-n-butylamine in 200 ml. of ethyl acetate was prepared and was shielded from light. To this solution was added, during 1 hr., 4.0 g. of octyl 5-diazoimidazole-4-carboxylate, and the resulting reaction solution was stirred at room temperature overnight. The mixture was then concentrated under reduced pressure to a thick syrup, which was dissolved in benzene and applied to a column of Florisil. The column was eluted successively with hexane, a mixture of hexane (60%) and acetone (40%). Evaporating the solvents under reduced pressure from the hexane-acetone eiiiuent, triturating the residual oil with hexane, and chilling the mixture resulted in the formation of light pink crystals that were separated by filtration, washed with hexane, and dried under reduced pressure: weight, 2.1 g.; M.P. 64-65 dec. The acetone efiiuent from the Florisil column was treated in the same manner as the hexaneacetone effluent and yielded an additional 967 mg. of faintly pink crystals of octyl 5(or 4)-(3-n-butyl-3-methyll-triazeno)imidazole-4(or 5)-carboxylate. The ultraviolet spectra of this compound in phosphate buffer solution at pH 7 showed absorption maxima of 37 m and at 330 m and in 0.1 N aqueous sodium hydroxide solution, at 249 m and 340 m Analysis.Calcd. for C H N O (percent): C, 60.50; H, 9.2-6; N, 20.75. Found (percent): C, 60.55; H, 9.24; N, 20.53.

EXAMPLE l2 Octyl 5 (or 4 3-cyclohexyl-3-methyll -triazeno) imidazole-4 (or 5 -carboxylate The procedure of Example 11 was employed with the following exceptions: (l) methylcyclohexylamine was used in lieu of methyl-n-butylamine and (2) the Florisil column was eluted successively with hexane, a solvent mixture composed of 50% hexane and 50% acetone, and a solvent mixture composed of 40% hexane and 60% acetone. Crystalline octyl 5(or 4)-(3-cyclohexyl-3-methyl-l-triazeno)imidazole-4(or 5)-carboxylate isolated from the two hexane-acetone efiluents by the procedure of Example 11 amounted to 3.3 g.; M.P., 94-95". Ultraviolet absorption maxima at 222 m and 326 m and at 249 mg and 340 m were present in the spectra of this compound dissolved in 0.1 N hydrochloric acid and in 0.1 N aqueous sodium hydroxide, respectively.

Analysis.- Calcd. for C H N O (percent): C, 62.78; H, 9.15; N, 19.27. Found (percent): C, 62.71; H, 9.10; N, 19.29.

EXAMPLE 13 Octyl 5 (or 4) 3 ,3-dimethyll-triazeno) imidazole- 4 (or 5 -carboxylate Dimethylamine gas was passed into 250 ml. of ethyl acetate until 65 g. had been absorbed. .To this solution, cooled in an ice bath, was added 7.0 g. of octyl 5-diazoimidazole-4-carboxylate during a period of one hour. The resulting solution was stirred at room temperature overnight and then treated with activated carbon. Evapora tion of the ethyl acetate under reduced pressure left the crude solid product which was purified by chromatography on Florisil by a procedure similar to those of Examples 11 and 12. The acetone efiluent yielded 5.8 g. of crystalline solid; M.P., 104-105. Alternatively, the crude product may be purified by treating an ethanol solution or an ethyl acetate solution of the crude material with activated carbon and then diluting the filtrates with water or with hexane, respectively. White crystals of octyl 5 (or 4)(3,3-dimethyl 1 triazeno)irnidazole 4(or 5 )-carboxylate so obtained melt at 104105 and display ultraviolet absorption maxima at 236 m and 329 me in phosphate buffer solution and at 249 my and 339 me in 0.1 N aqueous sodium hydroxide solution.

Analysis.Calcd. for C H N O (percent): C, 56.94; H, 8.53; N, 23.69. Found (percent): C, 56.90; H, 8.35; N, 23.74.

EXAMPLE 14 Octyl 5 (or 4)-aminoimidazole-4(or 5 )-carboxylate hydrochloride tion under a current of nitrogen, the filtrate was saturated with dry hydrogen chloride, and the mixture was concentrated under reduced pressure until a white solid (6.1 g.) remained. The white solid was dissolved in a mixture of 100 ml. of ether and ml. of ethanol, the turbid mixture was filtered, and the colorless filtrate was diluted, while hot, with 100 ml. of hexane. White crystals of octyl 5(or 4)-aminoimidazole-4(or 5)-carboxylate hydrochloride that precipitated from the cooled solution were separated by filtration, washed with a 1:1 mixture of ether and hexane, and dried under reduced pressure: 3

weight, 4.02 g.; M.P., 110. The ultraviolet spectrum of a 0.1 N hydrochloric acid solution showed maxima at 239 m and 266 my.

Analysis.-Calcd for c,,H ,N,o -Hc1 (percent): C, 52.26; H, 8.04; N, 15.24, Found (percent): C, 52.08; H, 8.04; N, 15.14.

EXAMPLE 15 Octyl 5(or 4)-nitroimidazole-4(or 5 )-carboxylate duced pressure until a white solid remained. Recrystallization of this residue from a mixture of ethanol and water yielded 5.925 g. of white platelets; M.P., 170171.

Analysis.Calcd. for C H N O (percent): C, 53.51; H, 7.11; N, 15.60. Found (percent): C, 53.86; H, 7.01; N, 15:68.

EXAMPLE 16 Methyl 5 (or 4)-[3-(p-chlorophenyl)-l-triazeno] imidazole-4 (or 5 -carb oxylate A solution consisting of 2.31 g. of para-chloroaniline in ml. of anhydrous ethyl acetate was prepared and was shielded from light. To this stirred solution was added, in portions, 551 mg. of methyl 5-diazoimidaz0le-4-carboxylate during a period of 15 min. The reaction mixture was stirred for an additional 20 hr. in the dark. The precipitated product was collected by filtration, washed thoroughly with ethyl acetate, and dried under reduced pressure at 56: weight, 657 mg. yield). This compound decomposes explosively at approximately 180- 185 and will decompose more slowly at lower temperatures.

Analysis.-Calcd. for C H ClN O (percent): C, 47.25; H, 3.61; N, 25.04. Found (percent): C, 47.47; H, 3.77; N, 25.02.

10 EXAMPLE 17 Methyl 5 (or 4) 3- 3 ,4-dichlorophenyl l-triazeno -4 (or 5 -carboxylate The procedure of Example 16 was employed except that a 10-fold molar excess of 3,4-dichloroaniline was used in lieu of para-chloroaniline. The yield of the first crop of the product was 34%.

Analysis.Calcd. for C H Cl N -O (percent): C, 42.05; H, 2.89; N, 22.30. Found (percent): C, 41.80; H, 3.22; N, 22.05.

Continued stirring of the filtrate from the first crop of product resulted in the precipitation of additional product that increased the yield to 52%.

EXAMPLE 18 Methyl 5(or 4)-(3-methyl-1-triazeno)imidazole- 4(0r 5)-carboxylate To a solution (shielded from light) of anhydrous methylamine in 20 ml. of anhydrous ethyl acetate at -5 was added, during a 5-minute period, 500 mg. of methyl 5-diazoimidazole-4-carboxylate. The reaction mixture was stirred for an additional 5 min., and the precipitated product was collected by filtration, washed with ethyl acetate, and dried under reduced pressure at room temperature: weight, 520 mg. (87% yield). The compound decomposes explosively at approximately -130. The analytical sample was dried under reduced pressure at room temperature for 40 hr. and at 56 for 1 hr.

AnaIysis.Calcd. for C H N O (percent): C, 39.34; H, 4.96; N, 38.24. Found (percent): C, 39.20; H, 5.10; N, 38.05.

EXAMPLE 19 Methyl 5 or 4) 3 ,3-dibutyl-1-triazeno imidazole- 4 (or 5 -carboxylate The procedure of Example 1 was applied to 1.41 g. of methyl 5(or 4)-arninoimidazole-4(or 5)-carboxylate with the following exceptions: a large excess of dibutylamine was used in lieu of 25% aqueous dimethylamine, the twophase reaction mixture was allowed to stir at 1520 overnight, and the isolation procedure differed in details as described below. The reaction mixture was extracted three times with ethyl acetate, the extracts were combined, and the total extract was washed with water and dried wih magnesium sulfate. Evaporation of the solvent left a syrup that was converted to a solid by trituration with a 95:5 mixture of cyclohexane and chloroform. The solid was collected by filtration, washed with cyclohexane, and dried under reduced pressure at room temerature: weight, 1.14 g.; M.P. 121. Concentration of the filtrate yielded a solid that was triturated with cyclohexane and separated and dried as before: weight, 1.1 g. (total yield, 80%); M.P. 121. The two portions were treated in hot ethyl acetate with activated carbon. Dilution of the filtrate with hot cyclohexane afforded 1.75 g. of white needles; M.P. 122-123 dec.

Analysis.Calcd. for C H N O (percent): C, 55.50; H, 8.24; N, 24.95. Found (percent): C, 55.38; H, 8.12; N, 25.16.

EXAMPLE 20 Ethyl 5(or 4)-[3-(2-hydroxyethyl)-3-methyl-1-triazeno]imidazole-4( or 5 -carboxylate The procedure of Part A of Example 8 was employed except that N-methylethanolamine was used in lieu of methyl-n-butylamine. The reaction mixture was diluted with cyclohexane; and after 0.5 hr. of stirring, the product was collected by filtration, washed with cyclohexane, and dried under reduced pressure at 56; yield, 75%; M.P. 138139 dec. This compound may be further purified by recrystallization from a mixture of ethanol and cyclohexane; M.P. 140 dec.

11 Analysis.-Calcd. for C H N O (percent): C, 44.80; H, 6.27; N, 29.03. Found (percent): C, 44.56; H, 6.23; N, 29.20.

EXAMPLE 21 Ethyl 5 (or 4) 3-methyl-n-octyl-1-tri azeno -imidazole-4( or 5 -carboxylate The method of Part B of Example 7 was employed except that methyl-n-octylamine was used in lieu of N- methylethanolamine and ethyl 5-diazoimidazole-4-carboxylate was employed in lieu of methyl 5-diazoimidazole-4- carboxylate. The reaction mixture, after 2 hr. of stirring, was diluted with cyclohexane. White crystals were collected by filtration, washed with a 1:2 mixture of ethyl acetate and cyclohexane, and dried under reduced pressure at 56; the yield from 400 mg. of the diazo compound was 510 mg. (69%); M.P., 124-125 dec. A specimen for analysis was recrystallized by dissolving it in ethanol, treating the ethanol solution was activated carbon, and diluting the filtrate with hexane; M.P. 125 dec.

Analysis.-Calcd. for C15H2qN5O2 (percent): C, 58.21; H, 8.81; N, 22.64. Found (percent): C, 58.37; H, 9.00; N, 22.78.

EXAMPLE 22 Ethyl 5 (or 4)-(3,3-dicyclohexyl-1-triazeno)imidazole-4(or 5 )-carboxylate The procedure of Example 21 was employed with the exception that dicyclohexylamine was used in lieu of methyl-n-octylamine. From 400 mg. of the diazo compound there was obtained 550 mg. (65% yield) of the desired product; M.P., 170-175 dec. An ethanol solution of the white solid was treated with activated carbon, the filtrate was diluted with cyclohexane, and the resulting solution was concentrated under reduced pressure to a white solid that Was washed with hexane and dried under reduced pressure at 56; M.P. l70175 dec.

Analysis.-Calcd. for C H N O (percent): C, 62.21; H, 8.41; N, 20.17. Found (percent): C, 62.11;. H, 8.42; N, 19.95.

EXAMPLE 23 Z-diethylaminoethyl 5 (or 4)(3,3-dimethyl-1-triazeno) imidazole-4 (or 5 -carboxylate The method employed W% similar to that of Example 1 with some modifications in the details of the operations. A solution of 130 mg. of sodium nitrile in 5 ml. of water was added at to a solution of 449 mg. of Z-diethylaminoethyl (or 4)-aminoimidazo1e-4(or 5 )-carboxylate hydrochloride in 25 ml. of 1 N hydrochloric acid, and the resulting solution was stirred at 0 C. for 45 min. The excess nitrile was destroyed by the addition of sulfamic acid, and 5 ml. of 25% aqueous dimethylamine was added. The mixture was stirred in the absence of light for 1 hr., saturated with sodium chloride, and extracted three times with 35-ml. portions of ethyl acetate. The extracts were combined, the total extract washed with water and dried with magnesium sulfate, and the ethyl acetate was evaporated. The residual oil crystallized: yield, 273 mg. (56.5%); M.P., 114. Extraction of the aqueous layer in similar fashion with two 50-ml. portions of chloroform afforded an additional 124 mg. (26% yield); M.P., 114. This compound may be recrystallized from a mixture of ethyl acetate and cyclohexane; M.P., 114.

Analysis.-Calcd. for C H N O (percent): C, 51.05; H, 7.85; N, 29.77. Found (percent): C, 51.14; H, 7.98; N, 29.92.

EXAMPLE 24 Z-diethylaminoethyl 5 (or 4) -(3-cyclohexyl-3-methyl- 1 -triazeno) imidazole-4 (or 5 -carboxylate The method of Example 23 was employed except that methylcyclohexylamine, in excess, was used in lieu of 25% aqueous dimethylamine, the reaction time was 2 hr. instead of 1 hr., and only chloroform (3 portions) was used to extract the product. The syrup obtained from the chloroform was applied to a column of Florisil. The column was eluted successively with hexane and with a 1:1 mixture of hexane and acetone. Evaporation of the solvents from the hexane-acetone eifiuent left a syrup that crystallized: yield, 52%; M.P., 118. The crude product may be purified by recrystallization from a mixture of ethyl acetate and cyclohexane; M.P., 124.

Analysis.Calcd. for C17H30N502 (percent): C, 58.25; H, 8.63; N, 23.98. Found (percent): C, 58.46; H, 8.37; N, 23.89.

EXAMPLE 25 Z-diethylaminoethyl 5 (or 4)-aminoimidazole-4(or 5 carboxylate hydrochloride A mixture of 1.0 g. of Z-diethylaminoethyl 5 (or 4)- nitroimidazole-4(or 5)-carboxylate hydrochloride, 100 ml. of ethanol, and 500 mg. of 5% palladium-on-charcoal catalyst was treated with hydrogen by the procedure of Example 14. After the catalyst had been removed by filtration, the solvent was evaporated under reduced pressure. The residual glass was allowed to stand under ethyl acetate. It crystallized and the crystals of Z-diethylaminoethyl 5(or 4)-arninoirnidazole-4 (or 5 )-carboxylate hydrochloride were collected by filtration, washed with ethyl acetate, and dried under reduced pressure at 56: yield, 810 mg. M.P., 142-144". An analytical sample was obtained by recrystallizing a 300 mg. specimen from a mixture of 4 ml. of ethanol, 12 m1. of ethyl acetate, and 15 ml. of hexane: recovery, 77%; M.P. l46148.

Analysis.Calcd. for c, ,H,,N,o,-Hc1 (percent): C, 45.72; H, 6.91; N, 21.32. Found (percent): C, 45.83; H, 6.80; N, 21.62.

COMPARATIVE EXAMPLE 26 Compound I, 5 (or 4)-(3,3-dimethyl-1-triazeno)imidazole-4(or 5)-carboxamide, has the same structure as Example 1 except that the ester group of Example 1 has been replaced by an amide group in Compound I.

Using the paper-disc, agar-difiusion assay (Pittillo et a1. Antimicrobial Agents and Chemotherapy) (1964), several important differences in antimicrobial activity were noed between Compound I and Example 1, as follows:

(1) At a concentration of micrograms per disc, Compound I did not inhibit the growth of any of the nonfila'mentous or filamentous fungi tested except for Penicillium rubrum. These assays included more than 25 strains of Candida albicans; 12. other Candida species, including Candida quilliermondii, Candida krusei, and Candida tropicalis; Hansenula wingei, Kloekera brevis, Saccharomyces cerevisiae, Saccharomyces carlsbergensis, Beauveria tenella, Fusariam oxysporum, Neurospom sitophila, Penicillium roquefiorti, Phycomyces nitens, and Rhizopus stolonijer. In contrast, Example 1 inhibited all of these fungi.

(2) Among the dysentery bacteria, Compound I did not inhibit the growth of three species (S. flexneri, S. dysenteriae, and S. boydii) of Shigella at 100 micrograms per disc; Example 1 did.

(3) Among the typhoid and paratyphoid bacteria, Compound I did not inhibit Salmonella typhemurium, S. asiaticus, S. cholaraesuis, and S. panama at 100 mcg./ disc; Example 1 did. Both compounds inhibited S. typhosa.

(4) Compound I did not inhibit Klebsiella pneumonz'ae, Sarcz'na lutea, or Lactobaczllus casei at 100 mcg./disc.; Example 1 did.

(5) At a concentration of 10 micrograms per disc, Example 1 inhibited Proteus mirabilis and 7 strains of Proteus vnlgaris; several strains of Pseudomonas aeruginosa; and more than 25 strains of Staphylococcus aureus. At the same concentration Compound I did not inhibit these bacteria except for a trace of inhibition of 2 strains of S. aureus.

(6) At a concentration of 1 mcg./disc, Example 1 produced inhibitory zones of 20 millimeters, or greater,

Example 1 in diameter in tests versus four species of the genus Mycobacterium; at the same concentration, Compound I produced only trace inhibition.

It is apparent that Compound I is not inhibitory to fungi, whereas Example 1 inhibits a broad spectrum of fungi. Furthermore, Compound I is inferior to Example 1 in antibacterial activity.

COMPARATIVE EXAMPLE 27 Using analogous procedures to those shown in Example 26, comparison below is given between two other compounds (II and 'III) of the carboxamide series with Examples 2 and 3 of the ester series of the present invention. These data likewise show the superior antimicro- 'bial activity of the triazenoimidazolecarboxylic acid esters in vitro.

i //N\/C-NH'3 l R; l I131 N=NN\ Compound II: R =nbutyl Example 2: Ra=nbutyl Compound III; R =cyclhexyl Example 3; R3=cyclohexyl -In the table all of the fungi that have been tested for sensitivity to all four compounds (Compound II, Compound II'I, Example 2, Example 3) are listed together with the zones of inhibition.

1 The numbers in the table beneath a compound are the diameters in millimeters oi the zones of inhibition, surrounding and including the paper disc (diameter=12.7 millimeters), produced by that compound. NT=not tested.

2 Mt. Vernon RI 180-1).

ATCC 4098. 7

Again, the carboxamide compounds II and III showed no fungistatic activity and limited antibacterial activity,

whereas the ester compounds of Example 2 and Example 3 showed activity in both microbial areas.

We claim:

R =C -C alkyl, diethyl aminoethyl, and mineral acid addition salts thereof R =C C alkyl, hydroxyethyl, cyclohexyl, and chlorophenyl R C -c alkyl, hydroxyethyl, cyclohexyl, chlorophenyl,

and hydrogen.

2. The compound according to claim 1, which possesses substituents such that at least one substituent of the group consisting of R R and R is CH 3. The compound according to claim 1, which possesses substituents such that at least one substituent of the group consisting of R and R is CH 4. Methyl 5(or 4)-(3,3-dimethyl-l-triazeno)imidazole- 4( or 5 )-carboxylate.

5. Methyl 5(or 4)-(3-n-butyl 3 methyl-l-triazeno) imidazole-4(or 5)-carboxylate.

6. Methyl 5(or 4)-(3-cyclohexyl-3-methyl-l-triazeno) imidazole-4(or 5 )-carboxylate.

7. Methyl 5(or 4)-[3-(Z-hydroxyethyl)-3-methyl-l-triazeno imidazole-4 (or 5 -carboxylate.

8. Ethyl 5(or 4)-(3-n-butyl-3-methyl-l-triaz/eno)imidazole-4(or 5 -carboxylate 9. Ethyl 5(or 4)-(3-cyclohexyl-3-methyl-1-triazeno) imidazole-4(or 5 )-carboxylate.

10. Ethyl 5(or 4)-(3,3-dimethyl-l-triazeno)imidazole- 4(or 5 )-carboxylate.

References Cited Shealy et al., J. Org. Chem., 27, 2150-54 (1962), QD 241 I6.

Shealy et al., Nature, 210, 2089 (1966), Q1N2.

JOSEPH REBOLD, Primary Examiner D. M. PAPUGA, Assistant Examiner US. Cl. X.R.

260-141, 999; 424-226 [soft copy] 

